<?php
namespace App\System\Component\Spl;

class SplStream
{

    private $stream;

    private $seekable;

    private $readable;

    private $writable;

    private $readList = [
        'r' => true,
        'w+' => true,
        'r+' => true,
        'x+' => true,
        'c+' => true,
        'rb' => true,
        'w+b' => true,
        'r+b' => true,
        'x+b' => true,
        'c+b' => true,
        'rt' => true,
        'w+t' => true,
        'r+t' => true,
        'x+t' => true,
        'c+t' => true,
        'a+' => true
    ];

    private $writeList = [
        'w' => true,
        'w+' => true,
        'rw' => true,
        'r+' => true,
        'x+' => true,
        'c+' => true,
        'wb' => true,
        'w+b' => true,
        'r+b' => true,
        'x+b' => true,
        'c+b' => true,
        'w+t' => true,
        'r+t' => true,
        'x+t' => true,
        'c+t' => true,
        'a' => true,
        'a+' => true
    ];

    function __construct($resource = '', $mode = 'r+')
    {
        switch (gettype($resource)) {
            case 'resource':
                {
                    $this->stream = $resource;
                    break;
                }
            case 'object':
                {
                    if (method_exists($resource, '__toString')) {
                        $resource = $resource->__toString();
                        $this->stream = fopen('php://memory', $mode);
                        if ($resource !== '') {
                            fwrite($this->stream, $resource);
                        }
                        break;
                    } else {
                        throw new \InvalidArgumentException('Invalid resource type: ' . gettype($resource));
                    }
                }
            default:
                {
                    $this->stream = fopen('php://memory', $mode);
                    try {
                        $resource = (string) $resource;
                        if ($resource !== '') {
                            fwrite($this->stream, $resource);
                        }
                    } catch (\Exception $exception) {
                        throw new \InvalidArgumentException('Invalid resource type: ' . gettype($resource));
                    }
                }
        }
        $info = stream_get_meta_data($this->stream);
        $this->seekable = $info['seekable'];
        $this->readable = isset($this->readList[$info['mode']]);
        $this->writable = isset($this->writeList[$info['mode']]);
    }

    public function __toString()
    {
        // TODO: Implement __toString() method.
        try {
            $this->seek(0);
            return (string) stream_get_contents($this->stream);
        } catch (\Exception $e) {
            return '';
        }
    }

    public function close()
    {
        // TODO: Implement close() method.
        $res = $this->detach();
        if (is_resource($res)) {
            fclose($res);
        }
    }

    public function detach()
    {
        // TODO: Implement detach() method.
        if (! isset($this->stream)) {
            return null;
        }
        $this->readable = $this->writable = $this->seekable = false;
        $result = $this->stream;
        unset($this->stream);
        return $result;
    }

    public function getSize()
    {
        // TODO: Implement getSize() method.
        $stats = fstat($this->stream);
        if (isset($stats['size'])) {
            return $stats['size'];
        } else {
            return null;
        }
    }

    public function tell()
    {
        // TODO: Implement tell() method.
        $result = ftell($this->stream);
        if ($result === false) {
            throw new \RuntimeException('Unable to determine stream position');
        }
        return $result;
    }

    public function eof()
    {
        // TODO: Implement eof() method.
        return ! $this->stream || feof($this->stream);
    }

    public function isSeekable()
    {
        // TODO: Implement isSeekable() method.
        return $this->seekable;
    }

    public function seek($offset, $whence = SEEK_SET)
    {
        // TODO: Implement seek() method.
        if (! $this->seekable) {
            throw new \RuntimeException('Stream is not seekable');
        } elseif (fseek($this->stream, $offset, $whence) === - 1) {
            throw new \RuntimeException('Unable to seek to stream position ' . $offset . ' with whence ' . var_export($whence, true));
        }
    }

    public function rewind()
    {
        // TODO: Implement rewind() method.
        $this->seek(0);
    }

    public function isWritable()
    {
        // TODO: Implement isWritable() method.
        return $this->writable;
    }

    public function write($string)
    {
        // TODO: Implement write() method.
        if (! $this->writable) {
            throw new \RuntimeException('Cannot write to a non-writable stream');
        }
        $result = fwrite($this->stream, $string);
        if ($result === false) {
            throw new \RuntimeException('Unable to write to stream');
        }
        return $result;
    }

    public function isReadable()
    {
        // TODO: Implement isReadable() method.
        return $this->readable;
    }

    public function read($length)
    {
        // TODO: Implement read() method.
        if (! $this->readable) {
            throw new \RuntimeException('Cannot read from non-readable stream');
        }
        if ($length < 0) {
            throw new \RuntimeException('Length parameter cannot be negative');
        }
        if (0 === $length) {
            return '';
        }
        $string = fread($this->stream, $length);
        if (false === $string) {
            throw new \RuntimeException('Unable to read from stream');
        }
        return $string;
    }

    public function getContents()
    {
        // TODO: Implement getContents() method.
        // 注意与__toString的区别
        $contents = stream_get_contents($this->stream);
        if ($contents === false) {
            throw new \RuntimeException('Unable to read stream contents');
        }
        return $contents;
    }

    public function getMetadata($key = null)
    {
        // TODO: Implement getMetadata() method.
        if (! isset($this->stream)) {
            return $key ? null : [];
        } elseif (! $key) {
            return stream_get_meta_data($this->stream);
        } else {
            $meta = stream_get_meta_data($this->stream);
            return isset($meta[$key]) ? $meta[$key] : null;
        }
    }

    public function __destruct()
    {
        // TODO: Implement __destruct() method.
        $this->close();
    }

    function getStreamResource()
    {
        return $this->stream;
    }

    function truncate($size = 0)
    {
        return ftruncate($this->stream, $size);
    }
}